JPH11223254A - Auto tensioner - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In an auto tensioner, wear between a bush and a collar is substantially eliminated, play and noise are prevented, and the life is extended. An auto tensioner has a casing.
And a plunger 8, and their respective mounting portions 12, 19
Each of the mounting holes 26 is provided with a through hole, and an assembly 27 is fixed to the inner periphery of each of the mounting holes 26. The assembly 27 has a cylindrical rubber bush 14, a cylindrical metal collar 13 vulcanized and fixed to the inner peripheral surface of the rubber bush 14, and a vulcanized adhesive fixed to the outer peripheral surface of the rubber bush 14. The outer cylinder 28 is press-fitted and fixed to the inner circumference of the mounting hole 26. The relative rotation generated between the mounting hole 26 and the collar 13 is absorbed by the elastic deformation of the rubber bush 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic tensioner for automatically applying an appropriate tension to transmission members such as an endless annular flat belt, V belt, toothed belt, and chain.

[0002]

2. Description of the Related Art As a conventional auto-tensioner, one disclosed in Japanese Patent Publication No. 2-500210 is known. 4 and 5 show a structure described in the publication, in which a V-belt 1 is wound around a pulley 2 and a play pulley 3. FIG. The idler pulley 3 is rotatably attached to the distal end of the arm 4, and the base end of the arm 4 is attached to the shaft 5 so as to be swingable.
A hydraulic auto tensioner 50 is connected to the center of the arm 4.

An auto-tensioner 50 includes a bottomed cylindrical casing 51, a cylinder 52 fitted in the casing 51, and a cylinder 52 through an open end of the casing 51.
A plunger 55 having a piston portion 53 which slides into and out of the casing 51 and a seal ring 54 provided at an open end of the casing 51 and in sliding contact with the plunger 55 are provided.

[0004] A mounting portion 56 formed on the lower surface of the casing 51 and a mounting portion 5 formed on the upper end of the plunger 55.
7 are provided with mounting holes 58, respectively. A cylindrical resin dry bearing 59 as a bush is inserted into the inner periphery of each mounting hole 58 with almost no interference.
A cylindrical metal collar 60 is inserted into the inner periphery of the dry bearing 59 with almost no interference. The collar 60 on the casing 51 side is connected to, for example, the immovable part 6 in FIG. 4, and the collar 60 on the plunger 55 side is connected to, for example, the arm 4 in FIG. Therefore, when the arm 4 swings, relative rotation occurs between the mounting hole 58 and the collar 60 at each of the mounting portions 56 and 57. The relative rotation of the mounting holes 58
Can be caused by sliding between the dry bearing 59 and the collar 60, but is mainly caused by sliding between the dry bearing 59 and the collar 60 having a small sliding area.

[0005]

As described above, the dry bearing 59 and the collar 60 have almost no interference.
The muddy water and the like easily penetrate between them, and the penetrated muddy water and the like promote the abrasion of the sliding surfaces of the dry bearing 59 and the collar 60.

An object of the present invention is to provide an auto-tensioner which solves the above problems, substantially eliminates wear between the bush and the collar, prevents rattling and abnormal noise, and can extend the life. Is to do.

[0007]

In order to achieve the above object, the present invention comprises a casing and a plunger which enters and exits the casing, and the casing and / or the plunger may be provided. )), A mounting hole is provided through each mounting portion, a cylindrical bush is inserted into the inner periphery of the mounting hole, and a cylindrical collar is inserted into the inner periphery of the bush. A bush, wherein the outer peripheral surface of the collar is bonded and fixed to the inner peripheral surface of the rubber bush, and the relative rotation generated between the mounting hole and the collar is absorbed by elastic deformation of the rubber bush. .

If the outer cylinder is bonded and fixed to the outer peripheral surface of the rubber bush and the outer cylinder is press-fitted and fixed to the inner circumference of the mounting hole, the rubber bush, the collar and the outer cylinder are assembled in advance. Can be treated as one assembly
Excellent in assemblability to mounting holes and exchangeability.

The rubber bush and the collar or the outer cylinder may be bonded and fixed by an adhesive, but is preferably fixed by vulcanization bonding of the rubber bush.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an auto tensioner according to the present invention will be described with reference to the drawings. The hydraulic auto tensioner 10 is a general-purpose product for automatically applying appropriate tension to transmission members such as an endless annular flat belt, V belt, toothed belt, and chain.
The structure between the auto tensioner 10 and the transmission member is not particularly limited, and can be used in place of the conventional auto tensioner 50, for example, as shown in FIG.

The auto-tensioner 10 of the embodiment shown in FIGS. 1 to 3 includes a bottomed cylindrical casing 11.
A press-fitted portion 15 having a reduced diameter is provided in the lower portion of the inner periphery of the casing 11, and an oil groove 16 is formed in the inner peripheral surface of the press-fitted portion 15 and the inner bottom surface of the casing 11. Casing 11
Inside, a bottomed cylindrical cylinder 17 having an outer diameter slightly smaller than the inner diameter of the casing 11 is inserted, and the lower end thereof is press-fitted and fixed to the press-fitted portion 15. A rod-shaped piston 18 at the lower end of the plunger 8 is slidably moved up and down with a predetermined clearance 30 into the cylinder 17 (high-pressure chamber 23 described later) from the open end of the casing 11.

A mounting hole 26 is formed in the mounting portion 12 formed integrally with the lower surface of the casing 11 and a mounting portion 19 formed integrally with the upper end of the plunger 8.
An assembly 27 assembled as described below is fixed to the inner periphery of 6. The assembly 27 includes a cylindrical rubber bush 14.
And a cylindrical metal collar 13 vulcanized and bonded to the inner peripheral surface of the rubber bush 14, and a metal outer cylinder 28 vulcanized and bonded to the outer peripheral surface of the rubber bush 14. The outer circumference of the outer cylinder 28 is press-fitted and fixed to the inner circumference of the mounting hole 26. As a method of assembling the assembly 27, the collar 13 and the outer cylinder 2 are formed on the inner and outer circumferences of the rubber bush 14 after molding and before vulcanization.
8 or the rubber bush 14 is formed by injecting rubber between the collar 13 and the outer cylinder 28 arranged on the same axis, and then heating the rubber bush 14 together with the collar 13 and the outer cylinder 28. Then, a method of performing vulcanization and simultaneous vulcanization bonding can be exemplified.

The collar 13 on the casing 11 side is connected to, for example, the stationary part 6 shown in FIG.
3 is connected to the arm 4 of FIG. 4, for example. Therefore, when the arm 4 swings, the mounting holes 12 and 19 are used in the mounting holes 26.
Relative rotation occurs between the rubber bush 14 and the collar 13, and the relative rotation is absorbed by the elastic deformation of the rubber bush 14. Since the rubber bush 14 and the collar 13 and the outer cylinder 28 are vulcanized and adhered, and the outer cylinder 28 and the mounting hole 26 are press-fitted so that they are all fixed so as not to be separated from each other. There is no sliding between them, and muddy water does not enter between them. Therefore, wear between them can be substantially eliminated, rattling and abnormal noise can be prevented, and the life can be extended. Note that arm 4
Of the mounting hole 26 and the collar 13
Is similarly small, and can be sufficiently absorbed only by the elastic deformation of the rubber bush 14.

A spring cover 41 is press-fitted and fixed above the plunger 8 and below the mounting portion 19. A return spring 44 is mounted in a compressed state between the lower surface of the ceiling portion of the spring cover 41 and the spring seat 40 installed on the upper surface of the press-fitted portion 15, and moves the plunger 8 in the retreating direction (upward in the figure). It is energizing.
A seal ring 20 slidably in contact with the outer cylinder of the spring cover 41 is attached to a stepped portion on the inner periphery of the open end of the casing 11 together with a ring fitting 21, and the seal ring 20 is fitted into a groove on the inner periphery of the open end. The stopper ring 22 is locked from below so as not to come off.

A high-pressure chamber 23 is formed between the inner peripheral surface of the cylinder 17 and the lower end surface of the piston 18. A low-pressure chamber 24 is formed between the outer peripheral surface of the cylinder 17, the inner peripheral surface of the casing 11, and the spring cover 41, and has a structure in which the hydraulic oil 7 is stored. The high-pressure chamber 23 and the low-pressure chamber 24 communicate in one direction via a check valve 25 provided on the bottom wall of the cylinder 17 and the oil groove 16. The high-pressure chamber 23 and the low-pressure chamber 24 are connected to the cylinder 17 and the piston unit 1.
The hydraulic oil 7 can also leak from the high-pressure chamber 23 to the low-pressure chamber 24 via the clearance 30 through the clearance 30 between the hydraulic oils 7.

An upper portion of the plunger 8 and a lower portion of the mounting portion 19 are provided with a rubber dust cover 32 which covers the opening end of the casing 11 from the plunger 8 and is arranged from the outer periphery of the casing 11. Dust cover 32
Moves up and down together with the plunger 8. The dust cover 32 includes a cylindrical portion 33 arranged on the outer periphery of the casing 11 and a plate-shaped lid 3 for closing the upper end of the cylindrical portion 33.
4 are integrally formed. An inner peripheral edge of the lid portion 34 is formed with a flange portion 9 integrally formed on an upper portion of the plunger 8.
And the upper surface of the ceiling portion of the spring cover 41 with a tight allowance, so that it is securely sealed.

When the auto tensioner 10 configured as described above is used, for example, as shown in FIG. 4, the plunger 8 urged upward by the elastic force of the return spring 44 tilts the arm 4 upward. The play pulley 3 can give the V belt 1 an appropriate tension. Further, at the time of overload, the hydraulic oil 7 in the high-pressure chamber 23 leaks from the clearance 30 to the low-pressure chamber 24, and the piston portion 18 can be made to enter the cylinder 17 deeply. Changes in belt length can be absorbed (automatically adjusted).

It should be noted that the present invention is not limited to the above-described embodiment, and may be embodied by appropriately changing the scope of the invention as follows, for example, as follows.

(1) The outer cylinder 28 is fixed to the inner periphery of the mounting hole 26 by caulking, welding, or the like. (2) The outer cylinder 28 is omitted, and the outer peripheral surface of the rubber bush 14 is directly bonded and fixed to the inner peripheral surface of the mounting hole 26.

[0020]

As described in detail above, according to the auto-tensioner according to the present invention, wear between the bush and the collar is substantially eliminated, and play and abnormal noise can be prevented.
It has an excellent effect that the service life can be extended.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an auto tensioner according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III of FIG. 1;

FIG. 4 is a schematic view showing an example of use of an auto tensioner.

FIG. 5 is a partially cutaway front view showing a conventional auto tensioner.

[Explanation of symbols]

 Reference Signs List 8 plunger 10 auto tensioner 11 casing 12 mounting part 13 collar 14 rubber bush 19 mounting part 26 mounting hole 27 assembly 28 outer cylinder

Claims (2)

[Claims] 1. A casing comprising: a casing; and a plunger which enters and exits the casing, and a mounting hole is provided in each mounting portion of the casing or the plunger, and a cylindrical bush is formed on an inner periphery of the mounting hole. In the auto-tensioner inserted, a cylindrical collar is inserted into the inner periphery of the bush,
The bush is a rubber bush, an outer peripheral surface of the collar is adhesively fixed to an inner peripheral surface of the rubber bush, and a relative rotation generated between the mounting hole and the collar is absorbed by elastic deformation of the rubber bush. An auto-tensioner characterized by comprising. 2. The auto tensioner according to claim 1, wherein an outer cylinder is adhesively fixed to an outer peripheral surface of the rubber bush, and the outer cylinder is press-fitted and fixed to an inner circumference of the mounting hole.